Core compositions



Patented Jan. 17, 1939 PATENT OFFICE 2,143,930 CORE COMPOSITIONS Nels G.Anderson,

Detroit, Mich., assignor to Aristo Corporation, a corporation ofMichigan No Drawing.

6. Claims.

This invention relates to cores and compositions for fabricating coresadapted for foundry use.

Core compositions have generally been produced from fine grained silica.sand, shore sand, sea sand, or equivalent fine grained material mixedwith a binder material usually termed a core oil. The core oil binderusually consists of various combinations of such materials as gum m orresin, drying oil such as linseed oil, or a mixture of drying oilsincluding linseed, castor, soya bean, or fish oils, and a diluent suchas kerosene. Cores are sometimes made from molasses and 5 water, butthis has been found unsatisfactory T since the cores crack adjacent thesurface thereof during baking and do notbake completely through, theodor and tendency of molasses to absorb moisture further rendering thismaterial unsatisfactory as a core binder.

It has been found that a solution of sugar and water may be employed totemper sand and the sand thus treated may be employed in conjunctionwith the usual amounts of any of the known types of core oils to producea stronger and more satisfactory core. It has also been found thatreduced amounts of core oil in combination with tempered sand, sandtreated with a sugar and water solution, will afiord strength of corescomparable with that of cores of untempered sand and the usual amount ofcore oil. Thus cores having much greater strength than usually efiectedmay be obtained at little or no additional cost and cores of the usualor greater than usual strength may be made at a much reduced cost.

The principal object of the invention is to improve the art of sandcores.

Another object is greatly to increase the strength of cores withoutmaterially increasing their cost of production.

A further object is to reduce the cost of cores having normal or greaterthan normal strength.

It is also an object of the invention to provide an improved method offabricating cores by tempering the same with a sugar-water solution andemploying the sand so treated in conjunction with reduced amounts ofcore oil, whereby to effect an improved core construction and to effectan economy in the cost of core production.

Other objects, features and advantages will w become apparent from thefollowing description and appended claims.

According to this invention, cores are made from a fine dusty sand, suchas shore or sea sand, or other available silica sand and the like,

' tempered by a sugar and water solution com- Application August 1,1935, Serial No. 34,221

prising approximately ten to seventy per cent granulated sugar or otherdesired types of sugars, such as glucose, syrups, and the like, andapproximately ninety to thirty per cent water. The sand thus tempered ortreated is mixed with any conventional type of core oil or bindermaterial, such as linseed oil, polymer oil, and the like. Polymer oilconsists of a mixture of polymerized diolefines resulting from bringingcracked petroleum distillates into contact with solid absorbents, suchas fullers earth, colloidal clays, char-, coal, and-the like. Theamounts of core oils employed in practice depends largely upon the sizeof the casting to be produced.

In making heavy castings, as low as twenty parts of tempered sand to onepart of core oil may be employed in the core composition, while inmaking cores for light castings, the ratio may be increased to as muchas two hundred parts of tempered sand to one part of core oil. Coresconstructed according to the principles of this invention are baked atapproximately the same temperatures and for approximately the sameperiod as in conventional core production, that is, at temperatures ofabout 400 F. and for a period of about two hours or less, a lower bakingtemperature and period being possible in the case of polymer oilbinders.

By way of example, it has been found that a core composition consistingof, by ,weight, sixty parts of sand, tempered or treated as aboveindicated by the addition of eight parts of the above specifiedsugar-water solution, and onehalf a part of polymer oil, or a similaramount of linseed oil, or other commercial core oils, produced a corehaving about double the strength of a core made up of sixty parts ofuntempei-ed or untreated sand and one part of linseed oil. The coreincluding linseed oil and untempered sand had a bond strength ofapproximately twenty pounds per square inch, under tension, while thecores made up of the same amount of sand, tempered by the sugar-watersolution and including one-half of the amount of either polymer orlinseed oil, had a bond strength of approximately forty pounds persquare inch, under tension.

The cost of the linseed oil was about sixty cents per unit weight, ofpolymer oil about fortysix cents per unit weight, and of granulatedsugar about 3.9 cents per unit weight, on the same basis Ailinseed anduntreated sand core weight of linseed oil had a bond about 20 poundsperg-square inch and strength or.

cost about {60 cents for the core oil, or three of bond strength.

cents per pound of bond strength. The core which included tempered sandand one-half unit of linseed oil produced a bond strength of fortypounds per square inch, under tension, and was produced at a cost of 30cents for the oil and three cents for the sugar-water solution, giving atotal bonding material cost of thirty-three cents, or approximately of acent per pound When one-half of a unit of polymer oil was employed withthe tempered sand, a bond strength of about forty pounds was eflected atan oil cost of about 23 cents and a sugar-water solution cost of threecents, or about of one cent per pound of bond strength. Thus, thetempered sand in combination with a reduced amount of core oil lessenedthe cost of cores in proportion to their strength in the ratio of. morethan three to one.

Core strengths may be varied by retaining a constant amount of anyconventional core oil and changing the amount of sugar-water solutionemployed or by retaining a constant amount of the sugar-water solutionfor the purpose of tempering or treating the sand and changing theamount of core oil used, the ratio of sand to core oil not being greaterthan 240 to 1.

A sugar-water solution alone does not provide a satisfactory core bindersince the core, during baking, cracks too rapidly adjacent the surfacethereof and does not bake through due to too rapid drying. The temperingsolution in combination with too small a proportion of core oil has asimilar eifect. A sufiicient amount of core oil delays drying and allowsthorough baking of the core.

The core composition, according to this invention, is preferably made bymixing sugar, water and sand and then mixing in the core oil. The ninetyto thirty per cent water and ten to seventy per cent sugar solution ispreferred and from one half to fifteen parts of the sugar-water solutionare employed to a hundred parts of sand, the number of parts of thesugar-water solution employed, decreasing as the sugar content of thesolution is increased. Because of the relatively higher costs of thecore oil, the minimum amount of this material is employed consistentwith the desired strength of the cores to be made. Acceptable results,howevcr,- may be obtained by thoroughly mixing sugar, water and oiltogether amaoao and immediately mixing'with sand, or the sand,,- sugar,water and oil may all be mixed at the same 1. A composition for formingcores which con sists of approximately twenty to two hundred and. fortyparts sand, one to thirty-six parts of a ten to seventy percent solutionof sugar in water for tempering said sand and one part of a bindermaterial selected from a group of substances consisting of drying oils,gums, and resins.

2. A composition for forming a binder material for a sand core whichconsists of approximately one to thirty-six parts of a ten to seventypercent solution of sugar in water for tempering the sand of the coreand one part linseed oil.

3. A composition for'forming a binder material ior a sand core whichconsists of approximately one to thirty-six parts of a ten to seventypercent solution of sugar in water for tempering the sand of. the coreand one part of a mixture of polymerized diolefines.

4. A composition for forming cores which consists of approximatelytwenty to two hundred and fortyparts of sand, one to thirty-six parts ofa ten to seventy per cent solution of sugar in water, and one part oflinseed oil.

. 5. A composition for forming cores which consists of approximatelytwenty to two hundred and .forty parts of sand, one to thirty-six partsof a ten to seventy per cent solution of sugar in water, and one part ofa mixture of polymerized diolefines.

6. The method of making a core which comprises tempering a fineaggregate by mixing therewith a sugar in water solution, then mixing thetempered aggregate with a binder material selected from a group ofsubstances consisting of drying oils, gums and resins, then forming suchmixture to the desired shape, and then baking the shaped mixture atapproximately 400 F.

NELS G. ANDERSON.

